Golf club and golf club head

ABSTRACT

A golf club whose balance adjustment is easily performed without reducing the strength of a shaft. A golf club basically comprises a head body  1  with one side; a hosel hole  4  with an opening on the one side; and a shaft  2  fitted thereinto. The hosel hole  4  comprises a first hole  5  extending from the opening; and a second hole  6  extending from a bottom of the first hole  5.  The first hole  5  allows the shaft  2  to be fitted thereinto, while the second hole  6  allows one of weight-adjustment balance weights  7  to be provided therein.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a golf club and a golf club head.

[0003] 2. Description of the Related Art

[0004] Due to the increased number of golfers, golf clubs have been manufactured by mass production. Golf clubs have respective centers of gravity (i.e., C. G.) determined at a stage of designing. If the weight of a shaft and a grip is determined, then the position of the center of gravity is determined by the weight of a golf club head. Therefore golf clubs have respective standard weight determined, corresponding to the respective positions of the C.G. In mass production, however, it has actually been impossible to manufacture golf club heads so that all of them may have the weight in accordance with the respective standards when they are finished. Accordingly, tolerance has been given so far to the standard weight so that golf club heads could be manufactured within the weight tolerance in a range of 4 g. For a head heavier than the standard weight, the balance adjustment thereof is generally difficult. For this reason, a head body has preliminarily been manufactured so that it may be lighter than the standard weight, while the short weight has been compensated for by putting a balance weight within a shaft when they are assembled.

[0005]FIG. 4 shows one example of conventional methods for adjusting the weight balance, in which a shaft hole 12 is formed in a golf club head 11, and after a shaft 14 is fixed in the shaft hole 12 with adhesive 13, metal powder 15 such as that of tungsten of a high specific gravity is measured to exactly weigh the deficit in weight, and then put into a cavity 14A of the shaft 14 from a grip side, said metal powder being fixed at the lower end portion of the shaft 14 by a plug such as a cork plug 16. Here reference numeral 17 in FIG. 4 denotes a ferrule.

[0006]FIG. 5 shows another example of conventional methods, wherein as the shaft 14 is bonded with the adhesive 13, a somewhat larger quantity of the adhesive 13 is put into the shaft hole 12. As the shaft 14 is made of a hollow pipe and the center portion thereof is hollow, an excessive amount of the adhesive 13 is allowed to get into the cavity 14A, so that a slender and cylindrical lead body 18 or the like can be put into the shaft 14 from the grip side prior to the solidifying of the adhesive 13 to thereby fix the lead body 18 while solidifying the adhesive 13.

[0007] However, there have been the following problems in these conventional golf clubs:

[0008] According to the conventional golf clubs of which the weight balance is adjusted by the foregoing former method, using the metal powder 15 as the balance-adjustment material, there has been such a problem that the position of the C.G. of the head deviates from what was originally designed because the metal powder 15 undesirably extends up to the grip portion in the cavity 14A due to the high void content of the metal powder as well as the high volume-to-weight ratio thereof when the inside diameter of the shaft 14 remains unchanged.

[0009] Moreover if the cork plug comes off, such problem arises that clattering occurs due to the metal powder 15 moving freely in the cavity 14A of the shaft 14.

[0010] According to the conventional golf clubs of which the weight balance is adjusted by the foregoing latter method, the method is advantageously simple as one has only to insert the lead body 18, yet it has a drawback that unless rapid work is done skillfully, the lead body 18 cannot be fixed as the solidification of the adhesive 13 proceeds. Further, to fix the lead body 18 firmly, the lead body 18 must be embedded into the adhesive 13 to some depth, which in turn means that the adhesive 13 extends beyond a line A at the upper end of the shaft hole 12 in the cavity 14A, In that case, however, the investigation by the present inventor has revealed that the mechanical strength of the shaft 14 is lowered by about 20-30% as a result. Although it is not necessarily clear what has caused such lowered strength, it is presumably due to the fact that if the adhesive 13 is solidified in a portion beyond the upper end A of the shaft hole 12 within the cavity portion 14, the elasticity of the shaft 14 is lowered at that portion, and thus the impact at the time of hitting or the like is transmitted directly to the shaft 14 without being reduced.

SUMMARY OF THE INVENTION

[0011] To eliminate the aforementioned problems, it is, therefore, an object of the present invention to provide a golf club in which the adjustment of the weight balance is easily performed without reducing the strength of a shaft.

[0012] It is another object of the present invention to provide a golf club head in which the adjustment of the weight balance is easily performed without reducing the strength of a shaft.

[0013] To attain the above objects, there is proposed a golf club according to a first aspect of the present invention, comprising: a head body with one side; a hosel hole with an opening on said one side of the head body; and a shaft fitted thereinto, wherein said hosel hole comprises: a first hole extending from said opening; and a second hole extending from a bottom of said first hole, said first hole having said shaft fitted thereinto, while said second hole having one of weight-adjustment balance weights provided therein.

[0014] Accordingly, the adjustment of the weight balance in a golf club can be performed simply by first inserting the weight-adjustment balance weight into the second hole and then fitting the shaft into first hole. Further, there can be obtained a good position of the C.G in the golf club as the weight-adjustment balance weight is disposed in the lowermost bottom portion of the hosel hole. Furthermore, no clattering occurs because no powder is used unlike conventional golf clubs. Additionally, there is no reduction in strength of a shaft because the adhesive does not need to be present in a portion beyond the upper end of the shaft hole in the hollow portion of the shaft.

[0015] There is also proposed a golf club head according to another aspect of the present invention, comprising: a head body with a hosel hole on one side, wherein said hosel hole comprises: a first hole extending from an opening of said hosel hole; and a second hole extending from a bottom of said first hole, said first hole having a shaft fitted thereinto, while said second hole having one of weight-adjustment balance weights provided therein, said weight-adjustment balance weights being prepared in order that the difference in weight relative to standard weight may be within 0.5 g. Accordingly it is possible to mass-product golf club heads whose weight is closer to the standard weight than those conventionally produced, and to easily achieve the weight balance set in advance to respective golf clubs.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is an exploded perspective view showing a golf club in accordance with an embodiment of the present invention.

[0017]FIG. 2 is a cross-sectional view illustrating a structure for attachment of a shaft in said embodiment.

[0018]FIG. 3 is an exploded perspective view showing a balance weight for adjusting weight.

[0019]FIG. 4 is a cross-sectional view showing a conventional structure for attachment of a shaft.

[0020]FIG. 5 also is a cross-sectional view showing another conventional structure for attachment of a shaft.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereunder is a description of an embodiment of a golf club and a golf club head in accordance with the present invention with reference to FIG. 1 through FIG. 3.

[0022] As shown in FIG. 1, a golf club of the present embodiment is an iron type golf club, comprising a metal head body 1 that constructs a golf club head and a shaft 2 that is a hollow pipe, said shaft 2 being fitted in a hosel hole 4 which is formed in a hosel portion 3 provided on one side of the head body 1.

[0023] A structure for attaching the shaft 2 is shown in FIG. 2. In the embodiment, a distal end of the shaft 2 is 9.4 mm in diameter, while said hosel hole 4 including a first hole 5 of a larger diameter and a second hole 6 of a smaller diameter formed at the lower portion of the first hole 5. The first hole 5 is formed to have a 9.5 mm φ diameter that is 0.1 mm larger than that of the distal end of the shaft 2 and to have a 29 mm depth. The second hole 6 is formed to have a 5 mm diameter that is smaller than that of the first hole 5 and to have a 5 mm depth.

[0024] The weight-adjustment balance weight 7 is housed in the second hole 6. Said weight-adjustment balance weight 7 is made of a tungsten alloy (the specific gravity: 17 to 18 g/cm3) manufactured by sintering process, and is formed into a short and columnar shape, of which the diameter and height are just enough to fit to the second hole 6. As shown in FIG. 3, a through-hole 8 is formed through the side face of said weight-adjustment balance weight 7 according to where it is necessary. By varying the size of the diameter of the through-hole 8, a plurality of the balance weights 7 each being of the same external shape but different in weight by 0.5 g, such as 4 g, 3.5 g, 3 g, . . . 0.5 g can be prepared beforehand. In the meantime, reference numeral 10 in FIG. 1 and FIG. 2. denotes a ferrule.

[0025] A golf club according to the foregoing structure can be produced in the following manner. That is:

[0026] In the first place, a head body 1 is manufactured by forging or the like, and then the difference between the weight of the head body 1 and standard weight is calculated so as to determine the weight to be adjusted. Thereafter, one of the balance weights 7 whose weight is the closest to the weight thus determined is selected so that the balance weight 7 thus selected is placed in the second hole 6 of the hosel hole 4 to thereby adjust the weight of the head body 1. Thereafter the adhesive 9 is applied to the distal end of the shaft 2 and the inner surface of the first hole 5 of the hosel hole 4, and then the shaft 2 is fitted in the first hole 5. As a result, a golf club with a correct position of the center of gravity as well as the excellent weight balance can be assembled. In that case, advance setting is desirable in order that the head 1 may be finished to a little lighter weight than the standard weight. In the case that the difference in weight between the head body and the standardized one is smaller than 0.5 g, any balance weight 7 does not need to be placed in the second hole 6, or otherwise, a lighter balance weight 7 made of a material of a low specific gravity such as plastic may be prepared beforehand to be placed in the second hole 6.

[0027] As aforementioned, a golf club according to the above embodiment comprises: the head body 1 having one side; the hosel hole 4 with an opening on said one side of the head body 1; and the shaft 2 attached thereto, wherein said hosel hole 4 comprises: the first hole 5 extending from said opening; and the second hole 6 extending from a bottom of said first hole 5, said shaft 2 being fitted into said first hole 5, while the weight-adjustment balance weight 7 being placed in said second hole 6.

[0028] Accordingly, the adjustment of the weight balance in a golf club can be performed simply by first inserting the weight-adjustment balance weight 7 into the second hole 6 and then fitting the shaft 2 into first hole 5. Further, good weight balance is achieved because the position of the C.G in the golf club can be free from substantial deviations as the weight-adjustment balance weight 7 is disposed in a portion of the head body 1 that is in the bottom of the hosel hole 4. Furthermore, no clattering occurs because no powder is used unlike conventional golf clubs. Additionally, there is no reduction in strength of a shaft because the adhesive does not need to be present in a portion beyond the upper end of the shaft hole in the hollow portion of the shaft 2.

[0029] Moreover, according to the head body 1 that constructs a golf club head of the present invention, a plurality of the balance weights 7 are prepared in order that the respective balance weights 7 may vary weight in units of 5 g, so that a tolerance of 0.5 g or below relative to the standard weight is achieved, thereby making it possible to mass-product golf club heads (corresponding to a head body 1) whose weight is closer to the standard weight than those conventionally produced. Specifically, as the weight-adjustment of the balance weights 7 is performed by forming the through-hole 8 in the balance weight 7 in the present embodiment, it is possible to prepare various weights each being of different weight but in the same external form, whereby the dimensions of the balance weights 7 can be in accord with that of the second hole 6 in diameter and depth so that the balance weight 7 can be fitted firmly and tightly.

[0030] Incidentally, the present invention should not be limited to the aforementioned embodiment, but various modifications are possible within the scope of the invention. For example, although the second hole 6 is formed round and the balance weight 7 is formed short and columnar in the aforementioned embodiment, the second hole 6 may be formed square, and the balance weight 7 cubic. Further, the first hole 5 and the distal portion of the shaft 2 may be each threaded so that both can be engaged to each other to be fitted. Although the first hole 5 is formed larger in diameter and the second hole 6 smaller in the aforementioned embodiment, both holes may be formed to define the same diameter. In that case, the holes 5 and 6 may be discriminated from each other in a manner that the portion in which the balance weight 7 is fitted defines the second hole 6, while the portion into which the shaft 2 is fixedly inserted defines the first hole 5. Moreover, although weight is adjusted in units of 0.5 g in the aforementioned embodiment, several balance weights with varying weight in units of 0.3 g for example may be prepared so that finer adjustment of weight may be possible, corresponding to the resultant smaller differences in weight. Alternatively, it goes without saying that the present invention is not limited to an iron type golf club, but may be applied to a variety of golf clubs such as a metal or wooden wood golf club that needs to be adjusted in weight. 

What is claimed is:
 1. A golf club which comprising: a head body with one side, a hosel hole with an opening on said one side of the head body; and a shaft fitted thereinto, wherein said hosel hole comprises: a first hole extending from said opening; and a second hole extending from a bottom of said first hole, said first hole having said shaft fitted thereinto, while said second hole having one of weight-adjustment balance weights provided therein.
 2. A golf club head comprising a head body with a hosel hole on one side, wherein said hosel hole comprises: a first hole extending from an opening of said hosel hole; and a second hole extending from a bottom of said first hole, said first hole having a shaft fitted thereinto, while said second hole having one of weight-adjustment balance weights provided therein, said weight-adjustment balance weights being prepared in order that the difference in weight between the golf club head and a standardized one may be within 5 g.
 3. A golf club according to claim 1, further comprising a through-hole formed through a side face of said weight-adjustment balance weight, wherein the adjustment of weight is performed by varying a size of a diameter of said through-hole.
 4. A golf club head according to claim 2, further comprising a through-hole formed through a side face of said weight-adjustment balance weight, wherein the adjustment of weight is performed in units of 5 g by varying a size of a diameter of said through-hole.
 5. A golf club according to claim 3, wherein said weight-adjustment balance weight is of a short and columnar shape.
 6. A golf club head according to claim 4, wherein said weight-adjustment balance weight is of a short and columnar shape.
 7. A golf club according to claim 5, wherein said weight-adjustment balance weight is made of tungsten alloy.
 8. A golf club head according to claim 6, wherein said weight-adjustment balance weight is made of tungsten alloy.
 9. A golf club according to claim 5, wherein said weight-adjustment balance weight is made of plastic.
 10. A golf club head according to claim 6, wherein said weight-adjustment balance weight is made of plastic. 